Dromochorus knisleyi, Duran & Herrmann & Roman & Gwiazdowski & Drummond & Hood & Egan, 2019

Duran, Daniel P., Herrmann, David P., Roman, Stephen J., Gwiazdowski, Rodger A., Drummond, Jennifer A., Hood, Glen R. & Egan, Scott P., 2019, Cryptic diversity in the North American Dromochorus tiger beetles (Coleoptera: Carabidae: Cicindelinae): a congruence-based method for species discovery, Zoological Journal of the Linnean Society 186, pp. 250-285 : 271-272

DROMOCHORUS KNISLEYI DURAN, HERRMANN,

ROMAN & EGAN SP. NOV.

( FIGS 7C , 8A , 9C )

Common name

Juniper grove tiger beetle.

Type locality

Vi c i n i t y o f Pe d e r n a l e s Fa l l s, Te x a s . H o l o t y p e ( USNM): 1 ♂, USA: Texas: Blanco Co. / Vicinity of Pedernales / 19-VI-2013 /leg D. Duran. Paratypes: 14 ♂♂, 19 ♀♀, USA: Texas: Blanco Co./Vicinity of Pedernales Falls St. Pk./19-VI-2013/leg D. Duran. 6 ♂♂, 7 ♀♀, USA: Texas: Blanco Co./Vicinity of Pedernales Falls St. Pk./08-VI-2015/leg S.J Roman. 5 ♂♂, 3 ♀♀, USA: Texas: Blanco Co./Vicinity of Pedernales Falls St. Pk./01-VI-2014/leg D. Brzoska. 2 ♂, USA: Texas: Blanco Co./Park E. of Pedernales Falls S.P./20-VI-2014/ leg D. Duran. 2 ♀, USA: TEXAS: Bandera Co./3 miles W of Pipe Creek/22-VI-2013/leg D. Duran.

Distribution

This species is only known from the Edwards Plateau of central Texas, locally known as the Texas Hill Country. It comes in close geographic proximity to D. belfragei and D. minimus , where all three species distributions converge at the edge of the Balcones Escarpment in Bexar County. Analyses of mtDNA data indicate that hybridization occurs in this contact zone, and apparent hybrid D. knisleyi x belfragei individuals have been found in this area.

Diagnosis

Dromochorus knisleyi is most easily confused with the sister taxa D. belfragei . For differential diagnosis, see D. belfragei species account.

Description

Medium-sized Dromochorus . Body length 10.9– 14.4 mm, mean ♀ 13.0 mm, mean ♂ 12.2 mm. Head slightly wider than pronotum. Head predominantly charcoal black with blue reflections mostly concentrated near the anterior margin and edges of the supraorbital region. Fine rugosity often present on the frons and vertex. All head portions glabrous except for two supraorbital setae next to each eye. Frons concave in median area, especially in male, bulging towards slightly convex near anterior margin, clearly delimited from clypeus, gradually blending into vertex. Genae black or bright polished metallic violet to blue, with shallow longitudinal striae gradually ending at border of vertex. Clypeus bronze with green to blue reflections throughout. Male labrum tridentate with 6–8 setae, central area pale ochre-testaceous, with a thin dark-brown to black border posteriorly and sometimes anteriorly, dark-brown to black laterally; the pale central area of the labrum may exist as a small spot, up to one-third of the total labrum surface; female labrum tridentate with 6–8 setae, entirely dark-brown to black with polished metallic cupreous to green reflections. All segments of maxillary and labial palpi consistently dark-brown; apical segment is not darker than other segments. Antennae normal length, reaching back to humerus and basal third of elytron, slightly longer in male than female; scape dark testaceous to black with metallic reflections of violet, cupreous and green, with 2–3 apical setae; pedicel dark testaceous with metallic reflections of violet, cupreous and green, lacking any setae; flagellum dark testaceous, antennomeres 3–4 with metallic violet and green reflections, densely clothed in short white setae, antennomeres 5–11 dull-textured without metallic reflections and possessing erect setae in apical rings only, covered with fine pubescence throughout.

Thorax: Pronotum 2.4–3.2 mm in length, mean ♀ 2.9 mm, mean ♂ 2.8 mm; width 2.5–3.2 mm, mean ♀ 3.0 mm, mean ♂ 2.9 mm. Pronotum charcoal black, with green to blue or violet reflections, especially along lateral margins, slightly wider than long, widest near anterior margin, width to length ratio 0.9 to 1.1, setae sparse to regularly spaced, mostly present along lateral third of dorsal surface; disc finely rugose, with thin but distinct median line, with well-defined shallow sulci present anteriorly and posteriorly; notopleural sutures clearly defined, not visible from dorsal view; proepisternum black with weak to strong iridescent blue to violet reflections, glabrous. Elytra elongate, 6.8–8.7 mm length, mean ♀ 7.9 mm, mean ♂ 7.7 mm, shape similar in both sexes, but slightly wider in female, especially toward apical third; sutural spine absent, microserrations not present on elytral apices; elytral dorsal surface convex; elytral texture dull, with regular small pits present throughout disk, elytral coloration charcoal black, often with blue reflections near humeral region; elytral maculations absent; two dark oblique infuscations present; subsutural foveae prominent, typically with metallic blue, green, or gold reflections.

Legs: Pro-, meso-, and metacoxae dark testaceous to black with iridescent blue to violet and cupreous reflections, sparse setae on pro- and mesocoxae, fewer on metacoxae; pro- and mesotrochanters with a single erect seta, metatrochanter glabrous, trochanters dark brown-testaceous; femora black with metallic violet and green reflections, densely clothed in decumbent white setae; tibiae testaceous brown, clothed with setae of two types: sparser brown-testaceous long setae and dense short decumbent white setae; two tibial spines present; tarsi brown-testaceous, first three dilated protarsomeres in male with dense greyishwhite setal pad.

Abdomen: Venter mostly black with occasional metallic green to violet reflections. Decumbent white setae present on ventrite 1. Ventrites 2–6 have sparse short brown erect setae present throughout, but often abraded.

Etymology

Named for Dr C. Barry Knisley, one of the leading authorities on North American tiger beetle conservation and ecology. D.P. Duran and R.A. Gwiazdowski are greatly indebted to Barry for his mentorship and friendship.

Ecology/natural history

Dromochorus knisleyi adults have been found from mid-May to late June, but it is likely that they could be active outside of this window.

Dromochorus knisleyi is found in upland juniperoak woodlands in the Edwards Plateau, and does not appear to be strongly associated with riparian areas. The preferred habitat is late succession stands of juniper and, as such, it can be difficult for a collector to easily walk through these areas. Adult beetles are active throughout the day and are present in semiopen grassy areas under the cover of juniper trees. The first author observed dozens of beetles over a span of two days, and all adult activity was restricted to these forested areas. Beetles foraged and mated exclusively near or under juniper boughs. Moreover, even during cloudy periods and late in the afternoon, none were observed moving into more open grassy areas outside of the juniper stands. Moreover, beetles were not present in woodlands dominated by oaks. In mixed juni-per–oak woodlands, beetles were found exclusively near junipers. This species may be the most ecologically specialized of all Dromochorus .

More observations are needed for this rarely collected species. Many aspects of the biology are currently unknown.

Figures

Figure 7. Labial palps of: A, D. pruininus; B, D. belfragei; C, D. knisleyi sp. nov. A and B illustrate labial palps with a contrasting darker apical segment, and C illustrates labial palps that are consistently dark throughout.

Figure 8. A, Elytra showing distinct punctures (foveae) running parallel to the suture of the elytra (D. knisleyi sp. nov.). B, lack of distinct subsutural foveae (D. welderensis sp. nov.).

Figure 9. Dorsal habitus for species of Dromochorus. A, D.pruininus; B, D.belfragei; C, D. knisleyi sp. nov.; D, D. minimus sp. nov.; E, D. chaparralensis sp. nov.; F, D. welderensis sp. nov.; G, D. velutinigrens; H, D. pilatei.